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Phrak
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Charge is conserved in particle interactions. Color is conserved. Inerial mass is conserved locally. Is weak hypercharge conserved?
I thought Jefferson Lab was a place were people study the strong interaction. Why did they decide to measure the weak charge ? Because they can ? Can they ? How difficult will this be ?Sideways said:By the way, Jefferson Laboratory in Newport News, Virginia is soon starting a major experiment to measure the weak charge of the proton.
humanino said:I thought Jefferson Lab was a place were people study the strong interaction. Why did they decide to measure the weak charge ? Because they can ? Can they ? How difficult will this be ?
Your statement is very misleading. It will take the entire tentatively scheduled beam time of JLab's Hall C for 3 years. Some people must have considered they had to deeply update JLab's mission. I'm not sure to get the point when I see the projected plotSideways said:It's a very tricky experiment; it will take something like a year of running time in one of the 3 research halls, if I recall correctly.
Sideways said:Yes it is.
The wikipedia article is pretty good if you want to learn more.
(By the way, Jefferson Laboratory in Newport News, Virginia is soon starting a major experiment to measure the weak charge of the proton.)
According to electroweak unification theory (part of the Standard Model), weak hypercharge ties directly into the electromagnetic properties of particles.
malawi_glenn said:electric charge is conserved if you do the Noethers theorem. Same with weak charge.
malawi_glenn said:Pick up any source on intro QED
malawi_glenn said:Well if you can agree that Maxwells equations state conservation of electrc charge then QED should have that property. I don't have my Weinberg at home, but if you have peskin the argument is in ch3 "quantization of the Dirac field", see page 62.
malawi_glenn said:oh let me see if I can help you with that, since you have that the Maxwell tensor (aka electromagnetic field tensor) is antisymmetric, we have [tex] \partial _\nu F^{\mu \nu} = 0 [/tex] so that we get the equation of continuity for electric charge. But another way to see this is by considering the action [tex] S = \int F^{\mu \nu}F_{\mu \nu} d^4x [/tex] and using noethers theorem on that one and euler lagrange equation of motion.
Weinberg is perhaps not the best place to start QFT... Mandl or Peskin is probably better introductory books.
Now I am not an expert on the electroweak theory (yet) but I have to say now that Vanadium seems to be entirely correct and that wiki article should be edited/motivated
Phrak said:malawi, thanks for all your help. I hope you keep this thread subscribed.
This is a very interesting issue for me. One the one hand, electric charge conservation is a direct result of simply imposing a 4-vector field on a (pseudo) Riemann manifold, of any Christoffel connection, and the definition of charge as the divergence of E--nothing more.
I don't know how far you've gone in the mathematical angle of differentiable manifolds, but charge conservation is summed-up in the statement, "All exact forms are closed."
On the other hand, the usual method of finding conservation laws is via Noether, as you know.
Are these two derivations the same or different?
It could be shocking and profound if they cannot be found equivalent.
I have to learn Noether.
malawi_glenn said:No Noether is as far as I know something different, but iam not 100% sure.
I've only done differntial geometry in class of General Relativity and one class in advanced analytical mechanics.
malawi_glenn said:The thing is that Noeather is for field theories, and you'll have noether in QFT's aswell.
Yes, I have seans notes, and I know from Rindlers books in SR how Fmu nu antisymmetri implies charge consv.
Vanadium 50 said:I can flip the spin with a magnetic interaction: [itex] e_L + \gamma \rightarrow e_R + \gamma[/itex], and now the left and right hand sides of the equation have different weak hypercharge.
The conservation of weak charge refers to the fundamental principle in physics that states that the total amount of weak charge in a closed system remains constant over time. Weak charge is a property of subatomic particles that determines their interaction with the weak nuclear force.
The conservation of weak charge is important because it is a fundamental symmetry of nature that is required for the consistency of the laws of physics. It also plays a crucial role in understanding the behavior of subatomic particles and their interactions.
The conservation of weak charge is related to other conservation laws, such as the conservation of energy and the conservation of electric charge, through the concept of gauge invariance. This means that the laws of physics remain unchanged when certain transformations are applied, including those related to weak charge.
While the conservation of weak charge is a fundamental principle, there are certain rare processes, such as beta decay, that can violate it. However, these violations are allowed within certain constraints and do not affect the overall conservation of weak charge in a closed system.
The conservation of weak charge has been extensively tested and verified through various experiments in particle physics. These experiments involve analyzing the behavior of subatomic particles and their interactions, and have consistently shown that the total weak charge in a system remains constant.